(a) Field of the Invention
The present invention relates to a method for monitoring a position of a vehicle in a lane of a roadway and warning the driver when the vehicle is moving out of the lane.
(b) Description of the Related Art
FIG. 1 shows a conventional device for monitoring a position of a vehicle in a lane of a roadway.
The conventional device comprises a CCD camera for taking a picture of a lane of a roadway and outputting image signals corresponding to the picture taken, an electronic control unit (ECU) receiving the image signals from the CCD camera and processing the signals according to a preset logic to determine if the vehicle is moving out of the lane, and an alarming device for outputting an alarm signal in accordance with signals transmitted from the ECU.
In such vehicle position monitoring technology, it is absolutely essential that the alarm signal is output in rear-time when the vehicle is moving out of the lane. Dire consequences may result from a delayed alarm signal. However, as is well known, since image signal data are usually large-scaled, powerful computing ability is required to process image signal data in real-time. This of course, leads to problems of high cost.
Accordingly, in the conventional device, a method in which the resolution of the image is lowered has been used. However, if the resolution of the image is too low, the device may not accurately determine the position of the vehicle in the lane. That is, the CPU may miscalculate and erroneously determine normal driving of the vehicle or straying of the vehicle out of the lane.
The present invention has been made in an effort to solve the above problems.
It is an objective of the present invention to provide a method for monitoring a position of a vehicle in a lane of a roadway and alerting the driver in real-time when the vehicle is moving out of the lane, thereby providing additional safety to the driver.
To achieve the above objective, the present invention provides a method for monitoring a position of a vehicle in a lane of a roadway. The method comprises the steps of inputting an image signal of a lane from a camera, eliminating noise of the image signal, dividing the image signal into a plurality of image frames having different resolutions, extracting a lane border by processing the image frames, modeling a road using the lane border, calculating an actual road width according to a distance between pixels on an image coordinate using a camera parameter calculated in accordance with a position of a camera, determining if the vehicle is moving out of the lane or not, and producing an alarm when the vehicle is moving out of the lane.
The step of dividing the image signal further comprises the steps of reducing the number of pixels of the image signal received from the camera to obtain the plurality of image frames, each having different numbers of pixels, and storing the plurality of image frames into a memory.
The step of extracting the lane border is conducted by processing the image frames, the image frames being processed in order of resolution from lowest to highest until a reliable lane border is extracted.